Buoyancy system



1970 J. WITCHER ETAL BUOYANCY SYSTEM 2 Sheets-Sheet 1 Filed Dec. 11, 1967 FFLL VALVE m "RB o 0 HT R 6 m 2 A m 4 n 2 G u 2 G O 2 m m: X a I 0v 4 F c l m D o wm OF- u 5 R o I YE-I INVENTORS. JAY WITCHER HERMAN S. KUNZ FIGZA V. C. MULLER ROY MILLER ATTORNEYS.

Jan. 1970 J. WITCHER ETAL 3,489,318

BUOYANCY SYSTEM 2 Sheets-Sheet 2 Filed D90. 11, 1967 United States Patent O 3,489,318 BUOYANCY SYSTEM Jay Witcher, China Lake, and Herman S. Kunz, Millbrae, Calif., assignors to the United States of America as represented by the Secretary of the Navy Filed Dec. 11, 1967, Ser. No. 689,572 Int. Cl. B65d 35/28 US. Cl. 222-95 3 Claims ABSTRACT OF THE DISCLOSURE Collapsible reservoir containing decomposable liquid, such as hydrazine, for inflating an underwater flotation bag, the end walls of which are spring urged toward each other which pressurizes the liquid above ambient pressure in proportion to the spring force applied to the end Walls and irrespective of depth of submergence.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION One of the present techniques of recovering sunken objects is to attach a deflated bag to the object and inflate it with gas to provide sutficient buoyancy to raise the object to the surface. Preferably, such a system should be approximately neutrally buoyant, prior to inflation, to facilitate transporting it to the sunken object which may be accomplished by a diver or a manned or unmanned vehicle. At great depths, beyond diving depths, the source of a gas supply for inflating the bag presents a problem since its container must be designed to withstand the great depth pressures and which may be variable over a considerable range.

SUMMARY OF THE INVENTION In the present invention the source of gas for inflating the buoyancy bag is a decomposable liquid, such as hydrazine normally used as a monopropellant, which is contained within a flexible bag the wall or walls of which are resiliently urged in such manner to reduce its volume. Since ambient pressure is transmitted to the liquid and since liquid is substantially incompressible the total pressure is ambient pressure plus the pressure exerted by the resilient urge. The pressure, above ambient, is the same for any depth of submergence and provides the necessary pressure for feeding the liquid to a decomposition chamber which supplies the buoyancy bag with gas.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 diagrammatically illustrates the various forms of the invention.

FIG. 2 is a longitudinal section through one form of liquid reservoir, when filled;

FIG. 2A is a like section with the useable liquid partially expended;

FIG. 3 is a longitudinal section through another form of liquid reservoir, when filled;

FIG. 3A is a like section with the useable liquid partially expended;

FIG. 4 is a longitudinal section through a further form of liquid reservoir, when filled;

FIG. 4A is a like section with the useable liquid partially expended; and

FIG. 5 is a section like FIG. 2 illustrating another form of spring means.

DESCRIPTION Referring first to FIG. 1, liquid container 10 is formed of flexible material, such as rubber or other elastomeric, having a cylindrical wall 12 and end walls 14, 1411. A fill valve 16 is affixed to either end wall and a discharge control valve 18, check valve 20, decomposition chamber or gas generator 22, and check valve 24 are series connected to a hose 26 which communicates with a buoyancy bag (not shown).

Referring to FIG. 2, end walls 14, 14a are sealingly connected to rigid plate members 28, 28a, between which extend one or more tension springs 30 of elastomeric material, such as rubber, which urges the end walls toward each other.

When the reservoir is to be filled, valve 16 is connected to a source of hydrazine under pressure which moves the end walls away from each other until the reservoir is cylindrical with flat end walls as shown in FIG. 2. The reservoir is then transported to the sunken object, along with the flotation bag, and attached to same, after which valve 18 is opened manually or by suitable instrumentation, permitting the hydrazine to flow to the gas generator and thence to the flotation bag. As shown in FIG. 2A, springs 30 exert forces on the rigid end plates 28, 28a, moving end walls 14, 14a toward each other, forcing the hydrazine under pressure to the gas generator. As will be apparent, the absolute pressure of the hydrazine is the ambient pressure applied through the flexible walls plus the pressure applied by the springs. The feed pressure of the hydrazine is thus the pressure applied by the springs which is the same at all depths.

FIGS. 3 and 3A illustrate another embodiment of the invention in which circular end plate 34 is secured to one end of slightly frustoconical bag 12a by a circumferential clamping band 36, circular end plate 34a being secured to the other end by a like band 36a. In this construction, the bag, when filled, is provided with an initial retroverted fold 38 and plate 34a moves toward fixed plate 34 under urge of a spring 30a, illustrated as a single tension metallic coil spring. As will be apparent, the type of springs illustrated in FIGS. 2 and 2A may also be employed in the construction of FIGS. 3 and 3A and vice versa.

FIGS. 4 and 4A illustrate another embodiment in which end plates 38, 38a are secured to diametrically opposite sides of a substantially spherical bag 12b. In this construction, the natural resilience of the bag material serves the function of the springs previously described. FIG. 4 illustrates the shape of the bag when filled under pressure, which expands in the same manner as a balloon. FIG. 4A illustrates the bag with the liquid partially expended, the tension in the bag wall providing the necessary pressure to the liquid to feed it to the gas generator. Some ullage will normally be expected when the liquid has been completely expended and in one form of successful construction the diameter of the expended bag is about one-third the diameter of the filled bag.

Another variation of the invention illustrated in FIGS. 2, 2A and FIGS. 3 and 3A employs compression springs rather than tension springs, these being external of the bag, as illustrated in FIG. 5. This figure illustrates two compression coil springs 30b for moving both end walls toward each other, particularly applicable to the bag construction of FIGS. 2, 2A. It will be apparent, however, that when applied to the construction of FIGS. 3, 3A only one spring would be required to move end plate 0 34a toward fixed end plate 34. It will further be apparent that a plurality of equi-angularly spaced compression springs may be employed, urging one or both of the end plates.

In the construction illustrated in FIGS. 2, 2A and 3, 3A, the bag may be reinforced with substantially nonstretchable reinforcing, such as woven fabric or the like, however, in the construction of FIGS. 4, 4a such reinforcing cannot be employed since it would defeat the resilience of the bag to collapse as the fluid is expended.

What is claimed is:

1. Apparatus for use with a buoyancy bag or the like for raising an object sunken in water, comprising;

a decreasable volume reservoir filled with a decomposable liquid, such as hydrazine, adapted to be submerged in the water for supplying the buoyancy bag with gas for inflating same,

the reservoir having a flexible wall with at lea-st a portion thereof under stress for applying pressure to the contained liquid, above ambient Water pressure during its decrease in volume, and

means for stressing said portion during its decrease in volume,

wherein said portion is stressed by at least one tension spring.

2. Apparatus in accordance with claim 1, wherein said flexible wall includes a circular outer wall portion and end walls closing same, at least one end wall forming a retroverted fold into the outer Wall at its juncture therewith adapted to shorten the length of the outer wall as it moves relatively to the other end wall.

3. Apparatus in accordance with claim 2, wherein both end walls form retroverted folds into the outer wall at their junctures therewith.

References Cited UNITED STATES PATENTS I 3,055,553 9/1962 Mapes et al. 22295 3,083,871 4/1963 Jepson 222212 X 3,199,726 8/1965 Pierson 22295 X 3,223,291 12/1965 Thomas 222-335 X DONALD F. NORTON, Primary Examiner 

